The Accuracy of Manual Muscle Testing

Manual Muscle Testing is a non-invasive assessment tool used by millions of healthcare practitioners worldwide for a variety of purposes. First described in the literature by Lovett and Wight in 1915, MMT was originally used to assess muscular weakness in polio victims. In 1949, physiotherapists Kendall and Kendall refined MMT into an art and science with the publication of their benchmark text, Muscles: Testing and Function. This type of MMT is still used today to assess neuromuscular integrity. In the 1960's, a different use for MMT was described by Dr. George Goodheart. In Goodheart's technique, called Applied Kinesiology (AK), MMT is used to evaluate a variety of additional functions of the body, apart from neuromuscular integrity. From Goodheart's work, many different techniques have emerged which use this second type of MMT. Moreover, it is estimated that over one million healthcare practitioners worldwide use this type of MMT: medical doctors, dentists, chiropractors, osteopaths, physiotherapists, other health professionals - plus even some lay-persons. As a result of this divergence, there exists two very different forms of MMT: (1) orthopaedic muscle testing to quantify muscle strength and asses neurological integrity, and (2) the other type of muscle testing - which called be called "muscle response testing" which is used to obtain additional information about a patient. What that information is depends upon the MMT system being used and what information is sought. It is this latter form of MMT that this proposed study will investigate. Therefore, for the remainder of this application, the term "MMT" will be used to refer only to the second type ("muscle response testing"). The basic premise of MMT is that when there is some aberrant nervous system input to a muscle, it is less likely to be able to resist an external force. During a manual muscle test, an external force is applied to one muscle or group of muscles which at first causes an isometric then an eccentric contraction. Consequently, the muscle being tested is labelled "weak" or "strong" based on its ability to resist this external force. A number of different techniques use MMT to test the body's physiological response to semantic stimuli, which may have both cognitive and emotional components. Monti et al. found that a MMT following congruent statements yielded significantly different results compared to a MMT following incongruent statements. A congruent statement is one that the person believes is true. An incongruent statement is one the person believes is false. The study by Monti et al. used self-referential statements similar to this study design, however they used statements such as, "My name is (insert one's name)". One criticism of using this type of self-referential statements is that in all likelihood both the muscle tester and the muscle testee know the verity of the statement, therefore, they are both unblinded, which may have introduced biased. While it is generally accepted by those who use this assessment tool that some bias exists in MMT, little is currently known about the degree of this bias. Therefore the main objective of this study is to investigate the accuracy of MMT to distinguish congruent from incongruent statements under varying degrees of blindness. A further aim of this study are to explore if practitioner experience correlate with MMT accuracy. Caruso and Leisman reported greater MMT accuracy in experienced practitioners compared to inexperienced practitioners. Therefore, this study will test the reproducibility of these findings. There will be two groups of participants selected for this study: (1) Practitioners, and (2) Testees - where the Practitioner will perform MMT on the Testee as the Testee speaks a statement. The Testee will know if s/he is speaking a true or false statement. However, for some statements, the Practitioner will be blind to the verity of the statement. Results will be analysed for percent correct - that is, percent of muscle tests which accurately predicted the verity of the spoken statement.